@spec identify(String.t(), map()) ::
  {:ok | :error, Rivet.Auth.Domain.t()}
  | {:exists,
     %Rivet.Ident.Email{
       __meta__: term(),
       address: term(),
       bounce: term(),
       id: term(),
       inserted_at: term(),
       primary: term(),
       updated_at: term(),
       user: term(),
       user_id: term(),
       verified: term()
     }}